Early Season Evaluation

BY Dairyland Seed Agronomy Team

One of the most important things to do after your crop is planted is to evaluate the crop. Early detection of a potential problem allows for the opportunity to correct those potential issues. Keep in mind that germination and emergence are greatly affected by moisture and temperature. Emergence can be delayed by up to three weeks if soil temperatures are 50-55°F or less. For optimal emergence and uniformity, the seeds need uniform planting depth, moisture, temperature and seed-to-soil contact.

Determine Plant Population

To determine the population of the existing stand measure 1/1,000^th of an acre by using the measurement in Table 1 that corresponds with your row width. Next, count the number of plants in the measured area and multiply that number by 1,000. Chose at least six representative locations across the field and average the populations to get the final plant population per acre

Stand Quality

Once we determine the population, then we can assess the quality of the stand. Ideally stand quality is assessed early enough to still be able to dig for seeds and late enough to know all the plants have emerged. This is usually around the V2-V4 stage for both corn and soybeans.

While walking the filed, pay extra attention to areas of the field that are slow to emerge or have missing plants. One of the first things to do in these areas is to dig up the seedling and check the planting depth. In most instances, we want corn planted 1.5 to 2 inches deep and soybeans 1 to 1.5 inches deep. Moisture and temperature extremes may increase those depths but hardly ever warrant shallowing up the depths.

After checking the planting depth, look for other possible planter issues, like singulation. Are there skips and doubles? Did the row shut-offs work correctly? Did we reach the desired planting population? If you are applying fertilizer through the planter then use this opportunity to evaluate how well the planter accomplished that task. Areas that did not receive the fertilizer will typically be a lighter shade of green and shorter. If an area received too much fertilizer or the fertilizer was placed incorrectly then the seedling could have cell desiccation or tissues damage.

Seedling diseases can also be the cause of a poor stand. When scouting for seedling diseases check for sunken or discolored mesocotyl, discolored leaf tips, brown roots, rotten seed or damping off. Some common soilborne seedling diseases for corn include Pythium, Fusarium and Rhizoctonia. In soybeans, common pathogens include Phytophthora, Pythium, Fusarium and Rhizoctonia.

Dead or missing plants can also be the result of insect damage. Early insect damage can occur above or below ground and affect the seed, roots or seedling. Look for misshapen seed, pruned roots, holes or feeding on the stem or in the leaves of the whirl. A few common culprits are seed corn maggots, wireworms, black cutworms, true armyworms and bean leaf beetles.

There are several factors that can hinder early season growth. It is important to thoroughly scout your fields early to determine the amount of quality plants in your stand. If the amount of quality plants in your stand is greatly reduced from your target population, replanting may need to be considered.

Estimate Yield Loss from Stand Reduction

Using Table 2 for corn and Table 3 for soybeans, we can estimate yield loss from the stand reduction and decide if replanting is going to achieve a greater return on investment versus your current stand.

While looking at the yield potential by population charts, be sure to factor in all costs before making a decision. There might be additional costs associated with extra tillage, planting costs, and pesticide applications.

If you have any questions on evaluating your early season stand please reach out to your Dairyland Seed dealer, DSM or agronomist.